Solar blocking window film?

[Canibul]

i've tried using search function for this but not having much luck. Our old boat has some dark window film on all of the inside windows. Makes it very dark inside. We assume this was added about 20 years ago to help cut the solar greenhouse effect. But our windows look black from the outside, and it is impossible to hold bare skin against the outside surface of the glass when the sun is directly on it. Inside surface is very warm, but not nearly as hot as the exterior. I am thinking there must be better products out now, with all the emphasis on reducing cooling costs.
Can anyone recommend a good interior solar film glass treatment for boats? We live and cruise in the tropics, so will always want to block solar instead of wanting the heating in the winter.

Is mirrored silver the best way to go? Does this turn a boat into a flashing strobe light in the daytime?

[CarlF]

The hot windows are because it's doing a good job. Otherwise that radiant energy is warming up the surfaces inside the boat. Those hot surfaces then warm the air in the boat.

You could experiment with a less dark film to see if you could get a better balance. I believe that some modern films block similiar amounts of energy without looking as black to the eye - but they still would get as hot.

You can find many options for film online (including Amazon) or get it from a local shop that does car windows.

Even an almost clear film will block 100% of the UV spectrum which is part of the heat but not the major part.

An alternative idea would be to make exterior shades from Phifertex. This blocks 90%+ of the sun but there's minimal contact between the fabric and the glass so very little heat transfers to the glass. The vinyl material also doesn't feel as hot as glass to the hand. You could leave the film in place for additional heat control. It's easy to buy a few yards of Pfifertex from Sailrite and tape it to the outside of the window to see how it works.

[hellosailor]

Go to 3M's web site, find their "window films" pages, find the local authorized dealer for them. Or if there isn't one on your island...find out what there is.


3M Crystalline is their top product, ranging from almost clear to very dark, and even the clear one blocks 99% of all UV and IR. Anything you can buy at a retail store will be much cheaper--but probably bubble or turn color as it ages.


"Boats" won't make a difference, since you're putting this stuff inside anyway. Look at comparisons for the automotive stuff, there are only a few companies making the really good stuff.


SOME of the films are based on metallic particles, others aren't. I don't think that would matter to you, but the ones with metallic particles of course also block radio waves to some extent. No big deal on a FRP boat.(G)


The same films are sold for home use, some extra thick so they reinforce glass against breakage. The "car" stuff is usually thinner and more conformal to curved surfaces, so either line should work well for you.


99% UV and IR block and almost clear...incredible, but it has gotten that good.

[redsky49]

I am assuming that the ports you have are tempered glass and not some variety of plastic.

Solar films ideally should be placed on the exterior of any glazing - ports and or hatches.

When the solar energy strikes the surface, the long waves of energy are altered and a large portion of the energy is immediately converted into sensible heat. That is what you are experiencing when you touch the exterior of the port. That heat is then radiated into the cabin as evidenced by the warm inner surface. The glass portion of your port simply has insufficient mass to retain any heat and rejects it into the boat interior. [Simplified explanation]

Reducing the solar gain from any transparent surface can be achieved in multiple ways. Screening (such as mosquito or basic window screening) can block anywhere from 30 -50% of the solar gain, and some purpose built screens will block even more.

Solar films have a range of solar coefficients depending on the purpose intended. If just desiring to reduce the fading of interior surfaces or fabrics, UV protection may result in film that appears to be a light gray or brown. These films still allow much of the visible light to pass.

If you are trying to block primarily heat gain to the interior, you will likely have a darker film that will also markedly decrease the light that enters the boat. For some people this may be unacceptable as this also restricts vision outward.

The mirrored surface films try to reflect rather than alter the solar energy and have issues of their own, particularly of appearance. I would suggest that you visit a marina and see for yourself if this would be acceptable. Note that there are also some color tints available with mirrored surfaces - some tending toward blue, purple or even green.

3M markets a large variety of films for commercial applications. Gila makes some consumer products, though my sense is that they are primarily auto focused. I am not aware of a specific marine solar film, primarily as the market is rather limited.

[Canibul]

So that's one vote for 3M Crystalline and they make other similar products, Thanks.

No 3M dealers here, and going to a marina here wouldn't really tell me anything about what solar film looks like. I basically have to make my decision based upon research, order it, import it, and then I own it. No such thing as warranty here. Not worth sending stuff back in most cases. So it's pretty important I make the right decisions, without ever seeing the product. It can get frustrating. I throw away quite a few bucks worth of brand new stuff a year.

[leftbrainstuff]

Originally Posted by redsky49

I am assuming that the ports you have are tempered glass and not some variety of plastic.

Solar films ideally should be placed on the exterior of any glazing - ports and or hatches.

When the solar energy strikes the surface, the long waves of energy are altered and a large portion of the energy is immediately converted into sensible heat. That is what you are experiencing when you touch the exterior of the port. That heat is then radiated into the cabin as evidenced by the warm inner surface. The glass portion of your port simply has insufficient mass to retain any heat and rejects it into the boat interior. [Simplified explanation]

Reducing the solar gain from any transparent surface can be achieved in multiple ways. Screening (such as mosquito or basic window screening) can block anywhere from 30 -50% of the solar gain, and some purpose built screens will block even more.

Solar films have a range of solar coefficients depending on the purpose intended. If just desiring to reduce the fading of interior surfaces or fabrics, UV protection may result in film that appears to be a light gray or brown. These films still allow much of the visible light to pass.

If you are trying to block primarily heat gain to the interior, you will likely have a darker film that will also markedly decrease the light that enters the boat. For some people this may be unacceptable as this also restricts vision outward.

The mirrored surface films try to reflect rather than alter the solar energy and have issues of their own, particularly of appearance. I would suggest that you visit a marina and see for yourself if this would be acceptable. Note that there are also some color tints available with mirrored surfaces - some tending toward blue, purple or even green.

3M markets a large variety of films for commercial applications. Gila makes some consumer products, though my sense is that they are primarily auto focused. I am not aware of a specific marine solar film, primarily as the market is rather limited.

Nice overview. Thanks.

Sent from my SM-N900T using Cruisers Sailing Forum mobile app

[hellosailor]

Canibul-
Pick any 3M authorized installer in, say, Miami. Whatever is a close large city where shipping will be the least problem. I'd call the installer, explain that you are on an island paradise where there are are NO local dealers, and you'd like to know if they can sell you material. And send you a couple of samples in the meantime. Since every job is cut from a stock roll and cut to fit, there's always plenty of scrap around, and that's all you need to see what it is.
Or, you might try calling 3M directly and again explaining. They usually have sample kits or sample folders that are available to the trade, and they might very well send one down to you gratis.
Their films are all designed for *interior* installation, since plastic films are easily scratched and abraded, even by routine dirt outside. As are all the similar films that I know of.
The only 'exterior' film is the top layer of Lexan MR-10, which is designed to be tediously removed and replaced from time to time, as it protects the heavier glazing under it.
The 3M window films, and pretty much everyone else's films, are normally wet with water (and a drop of detergent, or a similar magic spray) and then carefully squeegeed on and allowed to dry. Once they dry they adhere and shrug off water. If you chose to remove them, you cover them with an ammonia-soaked towel, cover that with plastic to trap the ammonia vapors, hit it with hot sunlight for a couple of hours, and it peels right back off again.
They DO make cheaper films than Crystalline, and if you are also looking for a tint, those may be good enough. I've seen the Solarshield (a lexan film designed to prevent broken glass coming into a building after explosions) that's was 15 years old, still crystal clear. Warranty should not be a worry with these products (G) but you might want to practice before you cut the final pieces. "Surgically clean" is a good way to start the surface prep.

If you don't get any samples, one way or the other, I know one dealer who'd probably take care of you. He's a stinkpotter, but at least those are boats.(G)

[Canibul]

Thanks. I'll check around and see what I can find. There are some auto parts stores that carry window tint, and of course many of the local youth have to replace their window tint every year on their cars. That's because the cops rip it off at registration renewal. It's possible one of the auto places carry it. There is a NAPA here.

[redsky49]

Don't over estimate the gains to be had from improvements in this area.

As a shoot from the hip SWAG, I would think that your ports and hatches (all glazed surfaces) constitute 5-10% of the total surface area of your boat. Another guess would be that the solar load due to the glazing might be 10-15%, at most 20%, of your total heat gain.

My reference books are all in storage now (mechanical engineer), but a ball park number for heat transfer from a solid fiberglass hull would be the equivalent of about R-3 or R-3.5. My guess is that a balsa cored deck would be in the range of R-5 or maybe a bit better. The point being that unless you have a purpose built insulated boat, the minor improvements gained in solar film (and subsequent reduction in heat gain) will likely be minimal.

I would venture that the best bang for the buck might be the mesh fabric mentioned in post 2.

Good luck with your project and post your results.

[CaptTom]

Originally Posted by CarlF

An alternative idea would be to make exterior shades from Phifertex. This blocks 90%+ of the sun but there's minimal contact between the fabric and the glass so very little heat transfers to the glass. The vinyl material also doesn't feel as hot as glass to the hand.

Is there anything like phifertex in self-adhesive vinyl?

I know I've seen a white mesh (or pattern of small "holes") that appeared to be thin vinyl material applied directly to the glass or plastic.

I'd love to apply something like this on an overhead hatch that's showing its age. The extra shade below would be nice, but I don't want to block out the light completely.

I can't seem to find this stuff on line. Maybe I'm using the wrong search terms.

[Mirage Gecko]

Originally Posted by CaptTom

Is there anything like phifertex in self-adhesive vinyl?

I know I've seen a white mesh (or pattern of small "holes") that appeared to be thin vinyl material applied directly to the glass or plastic.

I'd love to apply something like this on an overhead hatch that's showing its age. The extra shade below would be nice, but I don't want to block out the light completely.

I can't seem to find this stuff on line. Maybe I'm using the wrong search terms.

Pretty sure the stuff you want is called oneway also by 3M.
Used a lot here printed with advertising and put on bus windows.Quite expensive down this way but might be more realistic for you
Chris

[rourkeh]

I recently went through the same dilemma looking for a heat rejection film when I rebuilt all my hatches and installed new port lights. I am in the Caribbean so heat is a major issue all the time. I did a lot of research on window films and the bottom line is that all the products out there are heat absorbing film that do little to reduce the transfer of heat to the interior. I ended up purchasing V-Kool film V-Kool USA, Inc. | Best Window Film for Commercial, Residential, Homes and your Vehicles
which is a heat rejection product, the only one I could find. It is expensive, cost me $350 to do my 44' boat, but it rejects about 70% of the radiant heat as apposed to absorbing it ( huge difference ). V-Kool is the product used on almost all of the Mega Yacht glass applications and there is a dealer in Ft Lauderdale who will send you the film if you give him all your measurements. It is an almost clear film so there is no issue with loosing the available light or creating a cave affect. Using any other product will have very little effect on reducing the interior heat transfer.
Hope this helps.

[jaybird1111]

my wife works in canvas, so I can tell you a bit about the various products for window covers in fabric:

Phifertex shades about 70%, but you can see through it
Phifertex PLUS shades about 92.5%. You can sort of see through it. This is what I have on the outside of my salon windows, in a light color. Allows light through, also a fair bit of heat.
Sunbrella VIEW is the perforated sunbrella for shades/awnings etc. Don't think it's made anymore, but you might can find old stock

Darker your fabric, the more heat...

Our experimental solution has been to put aluminized mylar, the same as in car windshield shades, cut to fit the windows, reflective side out, UNDER the window shade/cover panels, but on the outside of the windows. Wow, has that cut the radiant heat. Still allows a fair bit of light, but of course absolutely opaque to view through. How long these things will last is anyone's guess, but they're cheap (I got two covers out of each $5 car-windshield panel)

[Canibul]

Originally Posted by rourkeh

I recently went through the same dilemma looking for a heat rejection film when I rebuilt all my hatches and installed new port lights. I am in the Caribbean so heat is a major issue all the time. I did a lot of research on window films and the bottom line is that all the products out there are heat absorbing film that do little to reduce the transfer of heat to the interior. I ended up purchasing V-Kool film V-Kool USA, Inc. | Best Window Film for Commercial, Residential, Homes and your Vehicles
which is a heat rejection product, the only one I could find. It is expensive, cost me $350 to do my 44' boat, but it rejects about 70% of the radiant heat as apposed to absorbing it ( huge difference ). V-Kool is the product used on almost all of the Mega Yacht glass applications and there is a dealer in Ft Lauderdale who will send you the film if you give him all your measurements. It is an almost clear film so there is no issue with loosing the available light or creating a cave affect. Using any other product will have very little effect on reducing the interior heat transfer.
Hope this helps.

Thanks for that info. We're halfway between Puerto Rico and Florida, so the sun is pretty fierce here year round. I've written V-cool already.

We're not interested in exterior covers. None of them last long enough here to be worth the investment. Inside the window glass seems to be fairly safe spot.

[gbohner]

3M Solar Film may not work for you. We have a lot of windows which got very hot and challenged the A/C. I decided to go with the 3M Solar product. The installer removed old tinted film from the inside and installed the 3M. No significant difference in heat. Here is my take on it. The glass was also heavily tinted. Sun passed through the tinted glass on the way in to the 3M Film, making the glass hot. Then it got reflected back through the tinted glass making it hotter yet. The glass got very hot and passed the heat inside, still challenging the A/C.